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Astronomers see bright impact on gas giant Jupiter
Posted: 11 September 2012

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jupiter-impact The impact captured on Video by George Hall in Dallas, Texas. Image: George Hall.

Amateur astronomers in the United States of America have reported a bright fireball in the Jupiter clouds tops as a result of an apparent impact. The first to see and report the event was amateur astronomer Dan Peterson from Racine, Wisconsin, who just happened to be observing the gas giant through his 300-mm LX200 'scope when the fireball burst into view; "This morning (9/10/2012) at 11:35:30 UT, I observed a bright white two second long explosion just inside Jupiter's eastern limb, located at about Longitude 1 = 335, and Latitude = + 12 degrees north, inside the southern edge of the NEB. This flash appeared to be about 100 miles in diameter. I used my Meade 12 LX200 GPS telescope and a binoviewer working at 400X for the observation, seeing was very good at the time. We'll have to wait and see if a dark spot develops inside the southern regions of the NEB over the next day or two. My best guess is that it was a small undetected comet that is now history, hopefully it will sign its name on Jupiter's cloud tops."

George Hall from Dallas, Texas, was imaging Jupiter at the time and he subsequently picked out a video frame showing the impact at 6.35am local Dallas time (11.35 UT).

It's likely that this impact was caused by a small asteroid or a comet striking the Jovian cloud tops, similar to the June and August 2010 events. The most famous event was back in 1994, when comet Shoemaker-Levy 9 slammed into Jupiter leaving huge, multiple scars that were easily observable by amateur astronomer's the world over. The question that astronomer's will be asking now is has the event dredged up any debris from deeper inside Jupiter that will be visible as marks in the cloud tops. Jupiter is under almost constant observation by amateurs around the world so it's likely we won't have to wait too long for the answer.

Jupiter is current in the morning sky among the stars of Taurus, rising around 10.30 BST and is sufficiently high enough above the eastern horizon by 2am to start observing. The impact site is on the southern edge of the North Equatorial Belt (NEB) at system II longitude of 219 degrees; as a guide the Great Red Spot (GRS) is at LII 182 degrees, although it is not that prominent so far this apparition. The impact site will have rotated to Jupiter's central meridian (an imaginary line draw from pole to pole down the centre of the Jovian disc) by 5.57am BST (strong morning twilight present), but will be visible on the disc 60-90 minutes earlier, from around 4am BST, when Jupiter will be 50 degrees up from London. Here are the impact transit times for the next week or so (times BST); 13th, 01.48; 15th, 03.27; 17th, 0505; 20th, 0234; 22nd, 0413.

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